#include <bits/stdc++.h>
using namespace std;

int main() {
	double longer;
	double distance = 2.0;
	double sum = 0;
	int flag = 0;
	cin >> longer;
	while (sum <= longer) {
		flag++;
		sum += distance;
		distance *= 0.98;
	}
	cout << flag;
	return 0;
}